class Solution {
public:
    int tribonacci(int n) {
        if (n == 0)return 0;
        if (n == 1 || n == 2)return 1;
        vector<int> dp(n + 1);
        dp[0] = 0, dp[1] = 1, dp[2] = 1;
        for (int i = 3;i <= n;i++)
        {
            dp[i] = dp[i - 3] + dp[i - 2] + dp[i - 1];
        }
        return dp[n];

    }
};